This invention relates to landing gears for model air planes and particularly to a landing gear that accommodates to the large impulsive torque to which the landing gear is subject when the model plane lands.
The landing gear of a model air plane is the supporting structure attached AT a lower level to wheels that are in contact with the RUNWAY (ground and, at an upper level, to the under surface of the airplane body. The most frequent occurrence of damage to a model airplane is the damage that the landing gear does to the airplane body when the plane lands. Damage with landing gears of the present art results from the horizontal shear that is developed as forward momentum of the plane is suddenly opposed by contact with the ground. In many instances, the landing gear is simply torn off the body.
The landing gear of the prior art includes simply a frame a pair of wheels that is bolted to the body.
U.S. Pat. No. 6,183,3331 to Lai discloses a landing gear seat (or channel), made of hard wooden or plastic material that straddles and abuts the central xe2x80x98fixing memberxe2x80x99 (union) of a landing gear having an extension on each end supporting a wheel.
The object of the invention is to provide an assembly structure for landing gear of a model airplane in which the landing gear is fixed on a landing gear fixing seat by fixing pins passing through the fixing seat. The pins are captured inside the plane by a pair of spring loaded nuts. The construction stresses the advantage of quick assembly/disassembly but does not claim any improvement over the existing art in resisting damage due to the destructive torques that lead to damage to the airplane body when the airplane encounters irregular terrain when landing. The springs, being on the inside of the airplane, only serve to maintain the landing gear in abutment with the plane body.
U.S. Pat. No. 5,129,596 to Wagener discloses a shock strut having a top end secured to the underside of the airplane body and the lower end mounted on a spring. The objective is to provide a design that ostensibly resembles a large plane.
It is an object of this invention to provide a landing gear for a model aircraft that is especially effective in resisting the shear forces generated when the landing gear of the air plane contacts the ground.
It is another object that the landing gear of this invention be mountable on surfaces of the aircraft that are normally horizontal (such as the under side).
It is another object that the landing gear be economical,
This invention is directed toward a landing gear including a support that is spring loaded so as to permit the support to rotate about a horizontal axis that is either parallel or perpendicular to the direction of travel when the wheels hit the ground. The support comprises a yoke including two legs, each having a wheel rotatably mounted on a lower end and a union section that joins the two upper ends of the legs. A The threaded ends of a pair of mounting bolts protrude through slot apertures in the union section and screw into blind nuts imbedded in the body of the airplane. A coil spring is mounted on each bolt and is partially compressed between a rubber washer against the head of the respective bolt and the union section of the support. Each spring and bolt therefore extend downward away from the bottom side of the union section and the body of the airplane. Therefore, the compressed spring forces the top surface of the union section directly against the underside of the airplane. The two slot apertures are aligned end to end and have a width that is slightly larger than the diameter of the bolt. The bolts are spaced from one another by a distance that equals the distance between the nuts in the body of the plane so that each bolt passes through one end of the respective slot closest to the end of the other slot.
The width of the slots is selected to allow the union section to tilt away from the surface of the airplane body by about 15xc2x0. For a union section made from 16 ga. sheet metal, the width of the slot will be about 0.030xe2x80x3 wider than the diameter of the bolts.
This selection of slot position and dimension permits the yoke to rotate either in a forward or reverse direction or from a side to side direction in response to encountering uneven topography of the landing strip. This action is enabled by springs whose axes bend in response to the applied forces but which are sufficiently compressed to restore the landing gear to its stable orientation where the axis of each spring is straight.
In another embodiment, a rubber sponge pad is interposed in the interface between the plane body and the union section which increases the shock absorbing capability of the landing gear.